Clarify that GHC must be version 8.10

Author: Tritlo

README.md

@@ -34,8 +34,8 @@ These are the versions we currently use - older versions might work too, please
 
 ## Usage
 -----
-This program requires version `3.4` or higher of `cabal`, and version `8.10` or
-higher of `ghc`. A complete environment required to run (minus the `QuickCheck`)
+This program requires version `3.4` or higher of `cabal`, and version `8.10`  of `ghc`.
+A complete environment required to run (minus the `QuickCheck`)
 is defined in `shell.nix`, and can be activated using `nix-shell`, if installed.
 
 **MacOS** users have to use `cabal configure --enable-optimization --enable-executable-dynamic`. Windows users might find some help [here](https://www.linux.org/pages/download/).